1. Field of the Invention
The present invention relates to an electron beam injection device for radio electric wave generators for ultra-high frequencies. It relates more particularly to a device for injecting an electron beam propagating along an axis in a cycloidal path under the action of a continuous electric field and subjected to a static magnetic field perpendicular to the axis and to the electric field.
2. Description of the Prior Art
This type of injection device may be used, in particular, in the new cyclotronic resonance masers proposed by the applicant in the new patent application filed on the same day as the present one and entitled "Radio electric wave generator for ultra high frequencies". In these generators based on an interaction of the cyclotronic type between an electron beam propagating between an electron gun and a collector and a high frequency electro magnetic field in a resonating structure, in which generator the electron beam moves along a cycloidal path in a transverse magnetic field under the effect of a deflection velocity created by a DC electric field, the injection device is formed solely by an electron gun subjected to a high magnetic field, identical to the one reigning in the resonating structure.
The electron gun used in this generator is formed by two facing electrodes one of which, the anode, is brought to a positive potential and the other, the sole, is brought to a negative or zero potential and a cathode positioned in the plane of the sole and brought to the same potential as this latter, at least one of the electrodes having a divergent profile such that the distance between electrodes increases from the cathode to the outside. With this type of electron gun, so as to obtain an electron beam propagating along a cycloidal path with a substantially constant radius of rotation r.sub.L, the voltage to be applied to the anode must be substantially higher than the supply voltage providing the energy of the electron beam.